Transmission line



May 24, 1932. .H. o. PETERSON 1,360,052

TRANSMISSION LINE Filed Dec. 8, 1928 2 Sheets-Sheet l Svwemtoz mom 0.PETERSON May 24, 1932. H. o. PETERSON 1,860,052

TRANSMISSION LINE Filed. Dec. 8, 1928 2 Sheets-Shec at 2 avwewtoz HAROLDo. PETERSON Patented May 24, 1932 UNEE .dTAlES FATE? HAROLD O. PETERSON,OF RIVERHEAD, NEW YORK, ASSIGNOR T0 RADIO CORPORATION OF AMERICA, ACORPORiTION 0F DELAWAR-E TRANSMISSION LINE Application filed. December8, 1928.

This invention relates to transmission lines, and more particularly to atransmission line system for conducting high frequency energy withoutradiation and pickup.

It is often necessary to transfer high frequency energy over atransmission line system, as for example from a transmitter to aremotely located antenna, or from a receiving antenna to a remotelylocated receiver, and in these cases it is respectively desirable toprevent radiation from or pick-up by the transmission line system. Thisis especially true in the case of directional antennas, for in such casethe direction and directive properties of the line usually differ fromthose of the antenna, and serve to distort the directive pattern of theantenna system.

To provide a simple transmission line system for conducting highfrequency energy without radiation or pick-up is the primary object ofmy invention, and to this end I pro vide a plurality of conductorsconnected electrically in parallel for conveying energy 1n onedirection, and another plurality of conductors for returning the energyconnected electrically in parallel and so located that the loci of theelectrical centers of both sets of conductors coincide. Sincealternating currents are being dealt with, the directions referred toare instantaneous only. With such an arrangement there is no physicaldis placement between the opposite electrical charges, and thereforeneither radiation nor collection of energy. In a simple and preferredform of my invention I employ four parallel conductors arranged at thecorners of a square, and at each end of the transmission line Ielectrically connect diagonally opposite conductors together.

With a transmission line system such as I have described it isexceedingly desirable to apply equal tension to each of the fourconductor's, in order that they may keep their relative spacingthroughout their length. For this purpose I employ a differentialsupporting system at one end of the transmission line, comprising apulley differentially supporting a pair of adjacent conductors, an otherpulley differentially supporting another pair of adj acent conductors,and a third Serial No. 324,595.

is desirable, a single post is used on one side of the line. To overcomethis is a further object of my invention, and for this purpose I provideshielding plates positioned symmetrically at either side of the line.

My invention is described more in detail in the following specification,which is companied by drawings in which Figure l is an arrangement of anantenna and a transmission line, in a typical installation; F igure 2 isa wiring diagram for a four Wire transmission line; Figure 3 is asection of the transmission line; Figure 4 is a section of a six wiretransmission line; Figure 5 is a cross section of an eight wiretransmission line arranged in a modified formation; Figure 6 is i adetail of a differential tensioning means for a four wire transmissionline; Figure 7 is an intermediate supporting means for the transmissionline; Figure 8 is a modification; and Figure 9 is a section taken on theline 99 in Figure 8.

Referring to Figure 1 it will be seen that there is a directionalantenna 2, supported between masts 4. and 6. The feeder members of theantenna, numbered 8, are connected to radio equipment in a remotelylocated building 10 by a transmission line 12. The transmission line andthe antenna extend in difierent-ly related directions. The transmissionline is supported at one or more in termediate points by supportingmeans l t, and is tensioned at one end by a tensioning weight 16.Jumpers 18 connect the transmission line 12 and the feeder members 8before the insulators 20 and 22. The impedance of the line is matched bythat of the antenna.

The transmission line preferably consists of four conductors, and theelectrical arrangement is shown more in detail in Figure 2, in which itis shown to consist of the conductors 31, 32, 33, and 34. Of these,conductors 31 and 33 are connected together at each end by leads 36 and38, While conductors 32 and 34 are connected together at each end byleads 40 and 42. The leads 36 and 40'are connected to the terminals of acoupling coil 44, while the leads 38 and 42 are connected to theterminals of a coupling coil 46. A source of energy 48 is coupled to thecoil 44, while a load 50 is coupled to the coil 46. In a transmittersystem 48 is a transmitter, and 50 is an antenna, while in a receivingsystem 48 is an antenna, while 50 is a receiver, although in: this casethe connections would preferably be made without transformers, the'lineimpedance being matched by proper design of the antenna. It will, ofcourse, be

appreciated that the transmission line is useful for carrying highfrequency currents from any unit of high frequency equipment to anyother. as well'as to or froman antenna.

A cross section of the line'shown in Figures 1 and 2 is given in Figure3, from which it will be seen that the four conductors are located atthe corners of a square, and that diagonally opposite pairs ofconductors are connected electrically in parallel. The electrical centerof the conductors 32- and 34 is at the geometrical center of the square,and the electrical'center of the conductors31 and 33 also is at thegeometrical center of the square, so that the centers-coincide. For theentire transmission line the loci of the centers coincide, and for thisreason there is no effective displacement in space between theelectrical charges of opposite polarity, and therefore neither radiationnor pick-up ocour.

The invention is not restricted to four conductors, and to illustrateanother number, reference may be made-to Figure 4, in which sixconductors 51, 52', 53, 54, 55, and 56 are employed. These conductorsare located at the vertices of'a regular hexagon, and alternateconductors, namely, 51, 53, 55, and 52, 54 and 56, are respectivelyconnected electrically in parallel at each end of the line by conductors58 and 60, as shown. In this case, as before, the loci ofthe electricalcenters of s the groups of parallel connected conductors coincide,thereby preventing radiation and pick-up.

I have indicated a preferred arrangement of eight Conductors in Figure.5. Referring to this figure it will be seen that the four con.- ductors,61, 62, 63, and 64 are arranged at the corners of a square, andconnected electrically in parallel, while the four conductors 71, 72,73, and 74 are arranged at the corners of a square of dillerent size,and also connected electrically in parallel. With an arrangement of thisnature. if one side of the transmission line is to be kept at groundpotential it is preferable to ground the outer conductors, that is, theconductors 61, 62, 63, and 64.

In order to keep the spacing of the conductors uniform it is desirableto tension each of the conductors equally, and for this purpose adifferential tensioning means may be'provided. Such an arrangement, asapplied to a transmission line of four conductors, is indicated inFigure 6, in which, incidentally, each of the conductors 31, 32, 33, and34 is provided with an insulator 81, 82, 83 and 84, be-

fore which the connecting links 38 and 42 are provided. Leads from thelinks 38 and 42 run to a supply. source or load 50. A loopof flexiblecord or wire 86- connects the insulators 8'1 and 82, and passes aroundtheperiphcry of a pulley wheel: 88, sothatthe conductors 31 and 32 aredifferentially supported thereby. A loop'of flexible wire'90is comnected to the insulators 83 and 84, and passes around theperiphery ofazpulley wheel 92, so

that the conductors 33 and 34" are difl'erentially supported thereby. Aloop of flexible wire 94 is connected to'the blocks of the pulleys 88and 92, and passes over the periphery of the pulley wheel 96, so thatthe pulley blocks are differentially supported thereby. Tensioningmeans, preferably init-he formof a large weight 98',- is applied, by wayof a fixed pulley 100, to the blockof the pulley In this manner equaltension is applied to each ofthe four conductors. By making-thediameters of the pulleys equal to the length of a side of the square atthe corners of which the transmission line conductors are located, thespacing 'of the conductors will not lie-dieturbed.

In a long line it may bedesirable to provide intermediate supports toproperly space the conductors, and this is especially necessary if theline is to be given horizontal or vertical changes in direction betweenits terminals.- Vertical changes in direction are sometimes desirable inorder to keep theline reasonably. parallel to the surface of the. groundover which it extends, though sudden changes in direction should beavoided to'prevent reflections. The intermediate supporting means shouldpreferably permit longitudinal movement of the conductors, to allow forthe action of the differential tensioning means already described. Onesuitable arrangement is indicated in Figure 7, in which there areattached to a supporting post 102 a plurality of insulation rollers 104,106 and 108. These so fit together, as shown, as to provide spaces inwhich the conductors 31, 32, 33, and 34 are confined, as regardstransverse displacement, though longitudinal displacement is readilypossible.

The post 102, being situated at one side of the line, is nearer to theconductors 31 and 34 than to the conductors 32 and 33, and there fore isapt to cause unbalance. That is, when dealing with radio frequencyenergies a ground may be established by a wooden pole; for, there issuflicient leakage for surface of a wooden pole to constitute anappreciable absorption of energy. To overcome this difficulty metallicplates 110 and 112 are provided, and these are positioned symmetricallyeither side of the transmission line, ant. are grounded to the post 102by the regular fastening bolts.

The arrangement shown in Figure '4", cmploying rollers, is morecomplicated than actually necessary when dealing with a portion of thetransmission line which is straight. In such casea modified formillustrated in Figures 8 and 9, is employed. lleferring to these figuresit will be seen that single insulation block 120, preferably isolantits,is used, and is provided with four holes 122, for supporting theconductors against transverse displacement. At either side of theinsulator 120 metallic plates 110 and 112 are provided, and the entirestructure is held together and afiixed to the post 102 by a single bolt124. The insulator 122 is enlarged to accommodate the bolt 124, as isillustrated by the cross section of the insulator shown in Figure 9.

I claim:

1. The method of transferring radio frequency energy without radiationor pick-up which includes conveying the energy in one direction along aplurality of paths located on the apices of a polygon, and returning theenergy in the opposite direction along a different plurality of pathslocated on the apices of a similar polygon the locus of the electricalcenters of which coincides with the locus of the electrical centers ofthe aforesaid paths.

2. A transmission line system for conducting high frequency energywithout radiation or pick-up comprising a plurality of conductorsconnected in parallel and located on the apices of a regular polygon forconveying energy in one c irection, and a plurality of return conductorsconnected in parallel similarly situated on a similar polygon withapices alternating with the first polygon and so located that the lociof the electrical centers of both sets of conductors coincide.

3. An open air transmission line system *for conducting high frequencyenergy without radiation or pick-up comprising an even numberedplurality of conductors arranged in open air at the vertices of aregular polygon, and means at each end of the transmission line forconnecting alternate conductors together.

4. A transmission line system for conducting high frequency energywithout radiation and pickup comprising an even numbered plurality ofconductors arranged at the vertices of a regular polygon, means at eachend of the transmission line for electrically connecting alternateconductors together, and tensioning means arranged to apply equaltension to each of the conductors.

5. A transmission line system comprising four conductors arranged at thecorners of a square, insulators at each end of the transmission line,means at each end of the transmission line for electrically connectingdiagonally opposite conductors together before the insulators, means tosupport one end of the transmission line, and means to support the otherend of the transmission line including a differentially yieldable memberconnected between a pair of adjacent conductors, another differentiallyyieldable member connected between the other pair of adjacentconductors, a third differentially yieldable member connected to thesaid other two members, and tensioning means connected to the thirdmember.

6. A transmission line system comprising four conductors arranged at thecorners of a square, insulators at each end of the transmission line,means at each end of the transmission line for electrically connectingdiagonally opposite conductors together before the insulators, means tosupport one end of the transmission line, and means to support the otherend of the transmission line including a pulley differentiallysupporting a pair of adjacent conductors, another pulley differentiallysupporting the other pair of adjacent conductors, a third pulleydifferentially supporting the blocks of the said two pulleys, andtensioning means connected to the block of the third pulley.

7. In combination, a directional antenna, remotely located radioapparatus, and a transmission line system therebetween comprising aneven numbered plurality of conductors arranged at the corners of aregular polygon and means at each end of the transmission line forconnecting alternate conductors together, whereby said transmission linesystem experiences neither radiation nor' pick-up which might affect thedirective pattern of the antenna.

8. In combination, a directional antenna, remotely located radioapparatus, and a transmission line system therebetween comprising fourconductors arranged at the corners. of a square, with means at each endfor electrically connecting diagonally opposite conductors together,whereby said transmission line system experiences neither radiation norpick-up.

9. In combination, a transmission line comprising a plurality ofconductors, arranged in open air at the corners of a square, a singlesource of supporting tension to be applied thereto, and differentialtensioning means ther-ebetween for applying tension from the sourceequally to each of the plurality of conductors.

10. In combination, atransmission line comprising; a plurality ofconductors, arranged in open air at the cornersof a regular polygon,means for supporting one end of the line, a single source of supportingtension to be aplied to the other end of the line, ditferentialtensioning means between the source and the line for applying tensionfrom the source equally to each of the'p'lurality of conductors, andintermediate supportingmeans for supporting the conductors againsttransverse displacement, while permitting longitudinal displacement.

11. In combination, a transmission line comprising a plurality ofconductors, arranged in open air at the corners of a regul'ar polygon,means for supporting one end of the line, a: single source of supportingtension to be applied to the other end of the line, difierentialtensioning means between the source and the line for applying tensionfirom the source equally to each of the plurality of conductors, andintermediate supporting means at substantially uniform heights aboveground for supporting the conductors against transverse displacement,while permitting longitudinal displacement. 1 2'. In combination, atransmission line system comprising four conductors arranged at the"corners of a square, means at each end for'electrically connectingdiagonally opposite conductors together, means for supporting one end ofthe line, a single source of supporting'tension to be applied to theother end of the line, difl'erential tensioning means between the sourceand the line for applying equal tension to each of the four conductors,

maintaining the four conductors in square formation, while permittinglongitudinal displacement.

1 3. The combination with a transmission line comprising a plurality ofconductors arranged in desired formation, and a supporting means forkeeping the conductors in that formation, of shielding means locatedsymmetrically with respect to the transmission lineat thev supportingmeans only and not intermediate the supporting means in order topreventunbalance of the line by the supporting means. i

14. system comprising four conductors arranged at the corners of asquare, means at each end for electrically connected diagonally oppositeconductors together, intermediate supporting means for said transmissionline, and conductive shielding means positioned symmetrically withrespect to the transmission line at the supporting means only and notintermediate the supporting means in v order toprevent the latter fromunbalancing the transmission line.

and intermediate supporting means for In combination, a transmissionline 15. In combination, a transmission line system comprising fourconductors arranged at the corners of a square, means-:at-each' and forelectrically connecting. diagonally opposite conductors together, meansfor supporting one end of the line, a; single source of supportingtension to'be applied: to the other end of the line, difierentialtensioning'means between the source and the linefor applying equaltension to each of the four conductors, intermediate supporting meansfor maintaining the four conductors in square form tion while permittinglongitudinal displacement, and conductive shielding means positionedsymmetrically with respect to the transmission line at each of theintermediate supporting means in order to prevent the latter fromunbalanci the line- HAR Lno. ISETERSON.

